Chronicles of my efforts to install a solar powered air conditioner into our shed.
Current Goal: 4 hours runtime
Current Ability: 45 minutes runtime (nonstop compressor)
(5) 100W Mono panels
(1) 20A Solar Charge Controller – MPPT (3 Panels)
(1) 20A Solar Charge Controller – PWM (2 Panels)
(1) 20A Solar Charge Controller – PWM (unused)
(1) 40A Triple CB
(1) 250A Termination Block
(1) 1500W Inverter – Pure Sine
(1) 150A ANL Fuse
(2) 12V Deep Cycle Marine Battery
(1) 410W Window AC unit
Batteries fully charged
1145AM – Winter
5 panels providing approx 300w
1145AM – SYSTEM OFF – 14V – 0 watts
1145AM – SYSTEM START – 13.8V – 60 watts load
1147AM – COMPRESSOR START – 12.9V -350 watts load (with 1300w short peak)
1201PM – 12.4v – 400 watts load
1210PM – 12.2V – 390 watts load
1215PM- 12.1V -TEST ENDED
1217PM – 12.8V
With the current configuration, I feel I can safely run the Air Conditioner for an hour without damaging the batteries but I know I can still do better.
Just purchased a 50Ah LiFePO4 battery, DC-to-DC charge controller, and (2) more 100W mono panels
The lithium battery isnt as big as I’d like, but I can parallel more of the same kind later
This DC-to-DC charge controller should allow me to start using lithium batteries without having to toss out my existing lead acid batteries, which I think may work for a few more years just fine.
I will have multiple sources of power (when all are above 13 volts):
–> 400watts into the solar input on charge controller (had to buy 30A capable cables to parallel 4 panels with MC4)
–> DC-to-DC charge controller is really designed for vehicle living, so the ‘Alternator’ input will be my existing batteries plus 300watts from my old MPPT charge controller
<– The charge controller will only allow 25A from each simultaneously for a total of 50A going into the lithium which is its maximum
The DC-to-DC charge controller will charge both battery sets as needed automatically
Eager to see what kind of performance I will get with the lithium having the existing lead-acid batteries to extend it, plus what should now be more than enough solar to keep it flying through the heat of the day
Here is a rough sketch of how things will look with all the new stuff, front and back…
(1) 150F Super Capacitor– This should help with voltage drop when compressor kicks in (from what I understand that is rough on the battery). Supercaps are known to greatly improve battery life and last a very long time, but supercaps are a bit cost prohibitive. It would seem to get the size needed to use my inverter with a constant load of 1200 watts I’d need 150F for my situation (I believe).
(1) 600W Grid-tie plugin inverter – Eventually I will produce more solar than I am consuming, so might as well throw that at our electric bill. From what I understand these are super easy, you just plug them into the wall to spin your meter backwards.